1. J. Frenkel, Üer die Wärmebewegung in festen und flüssigen Körpern, Z. Phys, p. 1, 1926.
2. P. Debye, Z. Phys., Feb. 1, 1935.
3. A similar view has been expressed by the writer in a book on the ” Theory of the Solid and Liquid States” (in Russian).
4. cf. J. Frenkel, loc. cit.
5. Phys. Rev., Dec. 1934.